Understanding the Bit Error Rate Tester and the Bit Error Rate

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A BERT – Bit Error Rate Tester – is a piece of equipment used to see how good the quality of a transmission is between single components of an entire system. There several building blocks to the bit error rate tester, being the pattern generator, the error detector (which connects to the test system or DUT), the clock signal generator, the digital communication analyser and the electrical-optical converter.

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The Bit Error Rate Tester and Test

Basically, the BERT or bit error rate tester is a way of testing circuits of digital communication. It uses a number of stress patterns that have been predetermined, operating according to logical sequences and a number of zero values.

There are a number of stress patterns most commonly used in BERT, being:

  • PRBS – which uses N Bits in its binary sequencer. These measure eye mask and jitter of TX-Data in optical and electrical data links.
  • QRSS – which is also a binary sequencer, generating every 20 bit word combination and repeating every 1,048,575 words. Additionally, it ensures there is never more than 14 consecutive zeros. It uses high and low density sequences, as well as sequences that change from low to high and high to low.
  • 3 in 24, which is a pattern with 15 consecutive zeros, the longest possible string, and looks at the lowest density of 12.5%. This stresses the minimum density as well as stressing the maximum consecutive zeros. This particular format may cause a yellow alarm.
  • 1:7, which is also known as one in eight. This has a repeating sequence of no more than 8 bit. It uses the 12.5% density, but this can be increased to 29.5% under B8ZS.
  • Min/Max, which is a very rapid pattern designed to go from low to high density. This is really useful in ALBO features.
  • Mark, or All Ones, which uses only one values in its pattern. This means that the top amount of power will be used. This should be ok under a properly regulated DC, but could set off a blue alarm if the pattern is unframed and leads to an AIS.
  • All zeros, which is like Mark, but then uses only zeros. This is used in order to find equipment lie radio and fibre multiplex.

There are many other types of BERT options out there. They are used by engineers and electrical experts in order to find errors and ensure all operations can run smoothly. The BERT takes away the danger of human error, as it is able to look at all eventualities through the various testing methods like 3 in 24 and Mark. This way, there is no need for complicated human calculations. Additionally, it is able to read through sequences and spot whether or not there are faults contained in those, something that would be impossible to do without a computerised testing feature. As such, the bit error rate tester is absolutely vital in the proper operation of electrical equipment.

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